Resistance unit



ug- 12, 1952 R. P. SWEGER 2,606,986

RESISTANCE UNIT Filed July 14, 1951 INVENTOR.

Russe# Pf mer BY caw] Wwf-(11% 14T TRN'YS Patented Aug. 12, 1952 l RESISTANCE UNrr Russell?. S-weger, Rockford, Ill., assigner to Barber-Colman Company, Rockford, Ill., a corporation of Illinois Application July 14,` 1951, serial No. 236,729

9 Claims.

This invention relates to resistance units of the type used in measuring surface temperatures, particularly those units in whichthe resistance element is a rigid disk or wafer.

The general object is to provide a new and improved mounting for a resistance element of the above character which is simple and inexpensive to construct and assemble, which may be clamped firmly against a supporting surface without danger of distortion or short-circuiting, and which is extremely sensitive to changes in the temperature of the supporting surface.

Another object is to mount the resistance element between two bars joined in a novel manner to form arigid assembly adapted to be mounted in a novel manner in an insulating casing. y

A further object is to mount the element as- Semblyvin the terminal block in a novel manner so as to prevent damage to the assembly during clamping of the block against a supporting surface.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a perspective view of the improved resistance unit.

Fig. 2 is a fragmentary bottom View.

Fig. 3 is a longitudinal sectional view takenv along the line 3-3 of Fig. 1.

Fig. 4 is an exploded perspective view of the parts of the resistance element assembly.

Fig. 5 is a fragmentary Sectional view taken along the line 5-5 of Fig. 3.

Fig. 6 is a perspective view of one of the electric terminals.

In the form shown in the drawings by way of illustration, the improved resistance unit comprises generally a plurality of resistance elements or so-called thermistors I electrically connected in parallel and disposed within a metallic bar-like assembly II which is seated in an in sulating block I2 adapted to be clamped by bolts I3 against a support I4 Whose temperature is to be measured. The elements I0 are in the form of wafer-like rigid disks which are relatively thin as compared to their diameter.

The assembly II includes an elongated channel I of highly conductive material such as silver having a iiat bottom and upstanding parallel anges I6 terminating in spaced tabs I'l. Seated within the channel is a channel-shaped bar I8 of insulation having spaced holes I9 each adapted to receive one of the resistance disks I0 with the lower end bearing against the bottom of the channel I5 and the top surface projecting 2 above the bottom of the channel I8. A highly conductive Strip 20 such as silver is laid across the tops of the disks I0 andcovered by a serpentine spring strip 2I with a layer 22 of insulation such as mica superimposed thereon.

The parts thus assembled are clamped together.v

by a metal bar 23 shorter than the channel I5 and having inverted J-shaped Side flanges 24V fitting down over the upstanding flanges I 5 of the channel I5 and apertured at 25 to receive the tabs I1. While the two channels I5 and 23` are pressed together, the tabs are bent inwardly to lock the channels together with the spring 2| holding the bars I5 and 20 in firm electrical conf tact with the ends of the resistance disks III.

The elongated bar-like assembly thus formed is seated in a recess 21 which is molded in the bottom of the block I2 between two parallel holes 28. To provide one contact terminal and Secure the assembly II in the block, elongated stripsv 29 are formed integral with opposite ends of the channel I5 and bent upwardly along the bottoms of Slots 30 extending along the inner sides of the holes 28. Above the block, the strips 29 are bent inwardly toward each other and thus are snubbed around edges 3| to lock the assembly firmly in the block.

The end portions 32 of the contact strips 29 are bent reversely and outwardly into horizontal positions where they are clenched by bent over lugs 33 against terminal washers 34 surrounding tubular studs 35 extending loosely through the holes 28. Dished spring washers 36 bear against the top of the block and press the terminal washers 34 upwardly against the shoulders 36a spun outwardly from the upper ends of the studs 35.

Square heads 31 vformed on the lower ends of the studs 35 are seated in correspondingly shaped recesses 38 in the bottom of block I2. The heads 31 terminate substantially flush with the exposed surface of the channel bar I5 which is pressed` into intimate heat conducting relation against the Support I4 when the block I2 is fastened to the latter by the bolts I3 which extend through the hollow studs. The latter are thus rigidly clamped to the support I4 but, owing to the sliding fit of the studs and the yieldable connection formed by the washers 36, the block I2 is `not subjected to bending stresses. Thus there is no danger of distorting or damaging the assembly II as an incident to mounting the unit on the support I4.

The bolts I3 constitute one terminal binding post. The other terminal is formed by a threaded stud 40 molded into the top of the block I2 near the center thereof and extending downwardly into a countersunk recess 4I in one end of the block. An extension 42 of the top connector strip is bent upwardly around the end of an insulating bar 43 pressed into the recess 4i. Above this bar, the strip 42 is bent inwardly and its end is riveted or otherwise secured at 44 to the inner end of the binding post 49.

I claim as my invention: s

1. A resistance unit comprising a channel of conductive material having a terminal strip projecting from one end, an insulating bar seated in said channel and having a hole therethrough,

a wafer-like resistance element disposed n said hole and abutting said channel, an insulated conductor lying against the other end of said' element and projecting from the end of said bar, and an inverted channel with anges telescoping with the flanges of said rst channel, and means interlocking said channels along opposite edges to clamp said element between said conductor and said first channel.

2. A resistance unit comprising a channel of conductive material having a terminal strip projecting from one end and tabs spaced alongand projecting from the edges of the channel flanges, anY insulating channel seated in saidrst channel and having a hole therethrough, a wafer-like resistance element disposed in said -holeand abuttingV said iirst channel, an insulated conductor lying in said second channel against the other end of said element and projecting from the end of the second channel, and an inverted channel with flanges telescoping with the anges of said first channel and having apertures at the base` of its flanges receiving said tabs, the latter being bent laterally to lock said -iirst and third channels together.

3. A resistance unit comprising a wafer-like resistance element, insulated conductive bars clamped against opposite end surfaces of said element and forming therewith relativelyv rigid assembly having insulated contact strips projectingfrom the ends of said bars, a block of insulation having a bottom recess receiving said assembly with one of said bars exposed for engagement with a supporting surface, a terminal postixed to said block and projecting from theblbck beyond one end of said assembly, onev of said projecting strips being connected to said-post,

and;` a second post projecting from saidblock intermediate the ends thereof, the other of said projecting strips being bent reversely within the block and connected to said second post.

4. A resistance unit comprising a wafer-like resistance element, conductive bars clamped against opposite end surfaces of said element and forming therewith relatively rigid assembly having insulated contact strips projecting from the' ends of said bars, a block of insulationrecessed to receive said assembly with one of said barsexposed for engagement with a supporting surface,

and' spaced terminals fixed to said block and respectively connectedl to said projecting strips.

5. A resistance unit having, in combination, a block of insulation having a bottom recess and spaced parallel holes through opposite endscommunicating `with' said recess beyond the ends of said'recessa resistance element disposed in said- -in said recess.

6. A resistance unit comprising a channel of conductive material having a terminal strip projecting from one end, a wafer-like resistance element disposed in said rst channel between the nanges thereof and abutting the channel bottom, a conductor lying against the other end 'of said, element within said channel and insulated from the latter, a bar disposed between the flanges of said channel and interloclied therewith to clamp said element between said bar and channel, terminal strips projecting from opposite ends of said channel, said element, said conductor and said bar forming a unitary assembly, an insulating block recessed? to receive said assembly and' having holes through which said terminal strips may be extended, andi means vsecuringl said strips to said block to fasten the assembly thereinA with saldi channel: exposed for contact with a supporting surface.

7. A resistance unit comprising a channel of conductive material having a terminal. strip projecting from one end, a wafer-like resistance element disposed in said rst channel between the flanges thereof andv abutting the channel bottom, a conductor lying against the other end'- of said element within said channel and insulated' from the latter, a bar disposed between the flanges of said channel' and interlocllzedA therewith toI clamp said element between saidV bar and channel', and insulated terminals projecting from the' ends-of said channel and said' conductor.

8. A resistance unit comprising a wafer-like resistance element, conductive bars clamped? against opposite end surfaces ci' said element and forming therewith relatively unitary assembly having insulated stripsprojecting from theends of one bar, and' ablock of insulationrecessed to receive said assembly with said one bar exposed on the bottom of the block for' eng-agement with av supporting surface, saidE strips being bent upwardly and around opposite end-portions of the block to fasten'saidassembly therein'.

9. A resistance unit having, inxcombina-tion. an elongated insulating block havingparallel holes extending through opposite ends, hollow studs extending through said holes and having shoulders at opposite ends, one of the shoulders being seated in said block, a resiliently lyieldable connection between theexteriorV of said block and thel other'of said shoulders, saidstuds` being adapted tok receive bolts by which the'studs may be clamped rigidly against a supporting surface without distortion of said block, anda resistance unit assembly mounted inoneside of said block andl adapted to be pressed against said supporting surface whensaidblock is attached thereto.

RUSSELL VP. SWEGER.

No references cited. 

